The present invention relates generally to a punch press having a pair of upper and lower tool holders mounted to automatically bring respective punch and die sets to a work station for punching a variety of holes in sheet materials. More particularly, the invention relates to an apparatus for rotating a set of punches and dies in a tool holder at a single punching station in the press in a manner such that each punch and die is rotatable within the tool holder for punching a wider variety of holes with a reduced set of tools.
U.S. Pat. No. 4,658,688, assigned to the assignee of the present application, the specification of which is incorporated by reference herein. This patent discloses a turret punch press having upper and lower turret tool holders which carry a number of punch and die sets in individual tool holding stations in the turrets. At least one of the corresponding tool holding stations in the upper and lower turrets is indexable to different angular orientations. Rotation of the indexable punch tools is accomplished by a slidably mounted motor for engagement with a timing pulley, which, through a timing belt and harmonic gear drive, acts to rotate the tool holder which carries the punch and die set. In this device, each of the turrets may be equipped with tool stations which receive tool support devices that are rotatable to selectively position the tools at chosen angular positions by rotating the tool sets about their longitudinal axes.
U.S. Pat. No. 4,569,267 discloses a punch press which uses a punch tool assembly which contains at least two punch pins of different diameters or cross-sections. The punch pins are interchangeable in the working position by a control element which is slidable or rotatable about a pin support member. When the punch tool assembly is rotatable about the ram to effect the movement of the punch pins from operative to inoperative positions, a cooperating movable die is provided in order to ensure that the aligned die bores are cooperatively dimensioned and configured with respect to the punch pins. The punch tool assembly is held on the ram and moves with the ram and the pins, when not being used, are held in an elevated position while the operative pin is rigidly locked into a protruding position.
It has also been known to provide multiple tool holding members to be dropped into the individual rotatable stations, for example a station of the general type referred to in the aforementioned U.S. Pat. No. 4,658,688. Such devices are commercially available and are known as "multi-tools". When assembled in a indexable station, the drive mechanism to rotate the indexable station will be affected to rotate the multi-tool carrying member so as to present individual tools thereof into a ram-actuable position.
In this manner, particularly when using a turret punch press, the punch press may be equipped with a plurality of circumferentially spaced individual tool receiving openings which are aligned between the top and bottom turrets such that the top turret carries a punch tool and the bottom turret carries a complementary die tool, each of which can be indexed by rotation of the turrets to a position at the work station under the ram. Further, one or more of the individual stations of the turret may be provided with indexing mechanisms such that individual tools carried at those stations may be rotated about their axes to provide different angular orientations under the ram. In this manner, openings of the same shape but different angular orientation may be provided in the work piece with the same punch and die pair.
Further, a miniature turret or tool carrier carrying a plurality of individually circumferentially spaced tools may be received in one of the indexable stations in a turret such that indexing of the indexable station will rotate a selected one of the punch and die tools to the ram actuating work station.
While each of these devices provides a singular increase in productivity, they are, at least for the last two mentioned styles of device mutually exclusive. Thus, a single station of a turret may provide rotatability for a single tool about its axis, or a multi-tool may provide rotatability for a plurality of tools to present them one at a time at a fixed angular position.